This nonprovisional application claims priority under 35 U.S.C. xc2xa7 119(a) on Patent Application No. 01850159.3 filed in Europe on Sep. 19, 2001, which is herein incorporated by reference.
The present invention generally relates to the field of manufacture and assembly of circuit boards. More specifically, the present invention relates to a system for handling components at a component mounting machine, the system comprising a plurality of component tapes, a plurality of component tape holders, each holder being arranged for holding a component tape, and a plurality of tape guides arranged for receiving a component tape and for bringing it in position for feeding and for picking components therefrom. The invention also relates to a tape guide for use in the system.
Generally, within the field of manufacture and assembly of circuit boards, electronic components are fed to a component mounting machine for mechanically and/or electrically mounting the components onto a circuit board. These surface mounted components are often delivered spaced apart along the length of a component tape. Generally, two different types of component tapes are used. The first type consists of a lower carrier tape, preferably plastic, provided with component holding compartments, which are enclosed by a separable, thin, plastic upper cover, or cover tape or protective tape. The second type consists of a cardboard body provided with through holes. The body is provided with separable, thin, plastic, top and bottom cover tapes, thus forming component compartments with the through holes. For ease of description, the term cover tape will hereinafter refer only to the top cover, since the bottom cover is generally not removed during the component mounting process. Consequently, the term carrier tape will hereinafter also refer to the cardboard body with the bottom cover tape provided thereon.
The component tapes are further provided with a lateral portion, extending next to the compartments along the entire length of the component tape, provided with through holes. These through holes are used for engagement with an element of a feeding device of suitable type, the feeding device feeding the component tape into position for picking of components from the tape.
After having positioned the electronic components in their corresponding compartments, the cover tape is attached to the carrier tape, and the component tape is wound on a component tape holder, which within the art generally consists of a component tape reel. Then, the component holder is transferred to a component mounting machine, which feeds a component to a certain predetermined picking position where it can be picked, or collected, by a pick-up head.
The attachment of the cover tape to the carrier tape can, for instance, be performed by providing areas on either or both of the cover tape and the carrier tape with adhesive, or areas where the cover tape is fused to the carrier tape. Generally, these areas are elongated and run along the entire extension of the component tape, along and adjacent to each side of the component compartments.
According to one method for exposing and picking a component from a component tape, a particular type of tape guide is used for bringing the component tape in position for feeding the component tape by interaction with a feeding device, and for picking of components from the tape. The tape guide is provided with an exposure device, the exposure device exposing the components at a picking position, by separating and lifting a portion of the cover tape from the carrier tape, and leaving the remaining portion of the cover at least partially attached to the carrier tape. Furthermore, the tape guide is releasably mountable in a component mounting machine, or in a component magazine for use in the mounting process by the component mounting machine, and virtually operates as an adapter between the component tape and feeding and picking devices of the component mounting machine. Thus, a component tape is preferably first loaded into the tape guide, and the loaded tape guide is then mounted in position in or at the component mounting machine. A more detailed description of the tape guide and the methods of using such a tape guide are disclosed in co-pending U.S. patent application Ser. Nos. 09/886,482 and 09/886,384, which are incorporated herein by reference.
The use of such a tape guide is advantageous in that, inter alia, it is easy to load the tape guide with a component tape, it is easy to mount the loaded tape guide in a component mounting machine, or in a magazine for use with the component mounting machine, and remove it therefrom, and the tape guide has a simple configuration and build-up without moving parts that is easy and cost-efficient to manufacture.
However, the result from using the above-mentioned method is not altogether satisfactory.
Thus, an object of the present invention is to provide an improved method of handling components using a tape guide as described above.
The present invention is based on the insight of using, for component tapes of the same width, different tape guides with specific component exposing devices for exposing the components carried by said component tapes, the design of said component exposure devices being dependent on the configuration of the component tape to be used with that tape guide, which configuration in turn is dependent on the size and configuration of the carried component. Thereby, use may be made of tape guides having a same or similar basic configuration and geometrical outline, but with different component exposure devices. Consequently, tape guides having one type of basic configuration are provided for handling component tapes with the same component tape width, wherein the tape guides are varied in terms of the design of the exposure device for the tape guide.
Furthermore, and according to preferred embodiments of the invention, use is made of visual markings for distinguishing between tape guides with different component exposure devices.
A significant advantage of the present invention is that it allows for the simply configured tape guides of the invention to be used independent of the type and size of different components to be handled and, in turn, of the configuration of the component tape on which they are provided. The invention also entails a facilitated handling in connection with the use of this type of component tape guides, since a minimum of auxiliary equipment and extra labor is required for handling a vast number of different component tapes and components.
It should be noted that the following description refers to component tapes having the same component tape width.
According to a first aspect of the present invention, there is provided a system for handling components at a component mounting machine, which system comprises a plurality of component tapes of a given component tape width, each component tape, in turn, comprising a carrier tape and a cover tape, and carrying components that are positioned in sequence on the carrier tape and are covered by the cover tape, wherein the component tapes have different configurations depending on the carried components. The system also comprises a plurality of component tape holders, each holder being arranged for holding a component tape, and a plurality of tape guides arranged for receiving a component tape of said given component tape width and for bringing said component tape in position for feeding of the component tape and for picking components from the component tape at said component mounting machine, wherein said tape guides are releasably mountable at said component mounting machine, preferably in a component magazine. Each tape guide is provided with a component exposure device, the exposure device exposing a component at a picking position by at least partly removing or displacing the portion of the cover tape covering said component. Also, said tape guides are divided into sub-sets of tape guides, wherein the tape guides of all sub-sets have a similar geometrical outline and basic configuration, and wherein the tape guides of each sub-set have component exposure devices of a same design which is different from the designs of the component exposure devices of the tape guides of the other sub-sets, the design of the component exposure devices within each sub-set of tape guides being dependent on said configurations of the component tapes intended for said sub-set of tape guides.
At present, there are a wide variety of different configurations for component tapes of the same component tape width. The thickness of the component tapes may vary, the size of the compartments may vary according to the components of the tape, the positions of the compartments, or rather the distance between the compartments, may also vary, as may the features of the cover tapes, both as to the positions of the adhesive or fused areas, as well as the width of the cover tape. However, the majority of components are provided on component tapes having a width selected from a few standardized component tape widths. For instance, at present approximately 80 percent of the components packed in component tapes and used in the circuit board assembling industry are provided on component tapes of 8 mm width.
Generally, each compartment contains one component only. Since the size of the components can vary greatly in component tapes of the same width, the size of the compartments varies accordingly. There must be sufficient space for accommodating the component, at the same time as there is a desire for the compartments to be small for limiting the movement of the component within the compartment, and for providing as many compartments as possible on the component tape. The difference in size refers to both the length and width of the compartment, as well as to the depth of the compartment. The depth of the compartment may also affect the overall thickness of the component tape. According to standardization protocols, the transversal center of each compartment is positioned at a defined distance from the lateral edge of the component tape. Thus, the distance from the lateral edge of the compartment to the lateral side of the component tape varies in accordance with the width of the compartment. Generally, the areas where the cover tape is attached to the carrier tape are positioned immediately adjacent to the lateral side of each compartment, i.e. between the compartment and the lateral edges of the component tape. For component tapes with very small compartments, these areas may be provided slightly spaced apart from the edges of the compartments. Furthermore, the width of the cover tape is generally the same for component tapes of the same width. However, there are exceptions where the width of the cover tape is varied within the same component tape width, essentially in correspondence with the width of the compartments.
The exposure device of a tape guide of the invention exposes a component by at least partly removing or displacing from the carrier tape the portion of the cover tape that covers the component. Preferably, this is performed by providing the exposure device with a separating portion that is brought into engagement with the component tape between the cover tape and the carrier tape, thus lifting the cover tape from the carrier tape. According to the present invention, the design of the exposure device is varied in accordance with the configuration of the component tape, in such a manner that the separating portion is brought into engagement with the component tape at the correct position. Thus, each tape guide is provided with an exposure device of a specific type adapted to the configurations of the component tapes for which the tape guide is intended. Consequently, the tape guides may be divided into sub-groups or sub-sets of tape guides, wherein the tape guides of all sub-sets have the same geometrical outline and basic configuration, while the design of the exposure devices of the tape guides varies between the tape-guides of different sub-sets. In other words, all tape guides within the same sub-set are adapted for handling the same multitude of types and configurations of component tapes with the same width.
In the following paragraphs, reference will be made to a component tape provided with two elongated adhesive areas provided on both sides of the compartments. However, the invention is also applicable to component tapes with other solutions for attaching the cover tape to the carrier tape, e.g. by fusing, at other or further positions, etc.
According to a preferred embodiment of the present invention, the separating portion of the exposure device is brought into engagement with the component tape at a lateral portion of the cover tape only. Thereby, a portion of the cover tape will be separated from the carrier tape on one side only, i.e. the cover tape will remain attached to the carrier tape on the other side of the compartment. Preferably, the separating portion has a width and is located at a position that is adapted to the configuration of the component tapes for which it is intended, i.e. to the width of the component compartments, the width of the cover tape and the positions of the respective adhesive areas. The width and position of the separating portion being such that the cover tape is separated from the carrier tape at one adhesive area, while leaving the adhesive area on the other side of the compartment at least partially intact, such that the cover tape remains attached to the carrier tape on that side of the compartment. According to this embodiment of the invention, a narrower separating portion is used for compartments having a smaller width.
Furthermore, according to preferred embodiments of the invention, the separating portion is arranged for advantageous engagement with the component tape essentially at the transversal center of the compartment, or in the vicinity thereof, which generally coincides with the transversal center of the cover tape, such that the tension in the cover tape is minimized during the separating procedure. This is advantageous in that it eliminates or at least significantly reduces the risk of the risk of possible ripping or cutting of the cover tape, which could lead to entanglement of portions of the cover tape that possibly might disturb the feeding of the component tape, as well as the picking of components. Preferably, the separating portion has a lateral extension in one direction that extends beyond the position of the adhesive area on that side of the compartment. Thus, according to this preferred embodiment, the width and lateral position of the separating portion is adapted to the configuration of the component tape, such that the separating portion is small enough and positioned to avoid separating the cover tape from the carrier tape at both sides of the compartment, and is wide enough and positioned for ensuring separation on one side of the compartment.
According to a preferred embodiment of the invention, the separating portion has a tongue-shaped tip portion that protrudes forward, i.e. against the feeding direction of the component tape. The tip portion preferably has an increased lateral extension in one direction for ensuring that the cover tape is separated from the carrier tape on one side of the compartment. The separating portion is further preferably provided with a wing portion for folding or bending the separated portion of the cover tape to the side, such that the compartment from which a component is to be picked is not at all covered by the covered tape.
According to an embodiment of the invention, the exposure device comprises a cover portion, which longitudinal extension is adapted to the configuration of the cover tape. Thus, for tape guides of different sub-sets for the same component tape width, the extension of said cover portion may vary. Preferably, the separating portion transcends into a cover portion that covers the component from the separating position to the picking position, such that the component is maintained in the correct position within the compartment. According to this embodiment, the extension of the cover portion is adapted such that a component exposed from the cover tape by the separating portion is covered by the cover portion until and including the position when the previous component is located at the picking position. Thereby, the described function of the cover portion is maintained regardless of the relative distance between adjacent component compartments.
Generally, the pitch of a component tape, i.e. the distance from the center of one compartment to the center of the adjacent or subsequent compartment, assumes a number of standardized values such that the majority of component tapes are provided with the same pitch. However, for component tapes carrying very large or very small components, the sizes of the compartments vary accordingly, thus making it impractical or impossible to maintain the same pitch.
For very small compartments, the standard pitch is decreased so that more components may be provided on each component tape, which entails that the distance between adjacent compartments may be very small. Preferably, the cover portion has a greater extension for component tapes provided with smaller compartments positioned at a reduced pitch, such that the cover portion covers the component tape closer to the picking position and, thereby, covers the next component to be picked. For larger components and compartments, the cover portion preferably has a smaller extension, such that the component tape is clear of the cover portion for a larger distance as counted from the center of the compartment that is located at the picking position, i.e. from the picking center. Thus, the cover portion will not interfere with the picking action, even though components are picked from compartments with a larger distance from the center to the rear edge of the compartments. Consequently, the extension of the cover portion is varied in accordance with the size of the compartments, and to the components contained therein, for component tapes of the same component tape width.
According to preferred embodiments of the invention, visual marking is provided for easily and quickly distinguishing between tape guides of different sub-sets. Thus, tape guides of the same sub-set of tape guides are provided with one or more visual markings that indicate to which sub-set the tape guide belongs. Then, the operator determines which visual marking indicates the tape guide to be used for a specific component tape, or component tape holder, and simply retrieves the tape guide having that marking. Thereby, the work for retrieving the tape guide to be used for a specific component tape is limited to a quick and easy visual identification.
The visual marking is provided on a portion of the tape guide which is easily visible or distinguishable both when the tape guide is mounted at the component mounting machine, and when it is not. Preferably, the visual marking is in the form of a label, preferably an adhesive label, or a small plate or inset, provided with a visual marking. Alternatively or additionally, the visual marking may constitute a part of the tape guide itself, e.g. the exposure device may be provided with a visual marking.
According to a preferred embodiment of the invention, the tape guide is provided with a protruding handle on which the visual marking is provided, e.g. as a label on the handle, an inset in the handle, or by providing the handle itself as a visual marking, e.g. with a specific color, shape, or the like.
According to a most preferred embodiment of the present invention, the visual marking is in the form of a specific coloring, which may be a single color or several colors. Thus, all tape guides within the same sub-set are provided with visual marking of the same color. According to other embodiments, the visual marking is in symbol or text form or in the form of patterns. These forms of visual markings may of course also be combined in order to enhance the ease of distinguishing between the tape guides of different sub-sets.
According to a specific embodiment, the exposure devices are provided with a visual marking. As an example, the exposure devices may be provided in different colors or with different patterns, whereby all similar exposure devices are provided in the same color or with the same pattern.
According to another embodiment, at least part or all of the tape guide is provided in a specific color or with a specific pattern. Then, all tape guides within the same sub-set have the same color or pattern, which differs from the tape guide colors or patterns of the tape guides of the other sub-sets.
It should be noted that although a number of different types of markings have been exemplified above, the term marking is to be interpreted in a broad sense, i.e. including all type of markings that may be used in distinguishing purpose.
According to further embodiments of the present invention, the component tape or the component tape holder, or both, is provided with a visual marking for facilitating the selection of which tape guide to use for a specific component tape. Preferably, but not necessarily, the visual marking correspond to that of the tape guide, i.e. the visual markings having the same pattern(s), symbol(s), color(s), or text, respectively. Then, the operator readily realizes that for a component tape, or component tape holder, with a specific visual marking, a tape guide with a corresponding marking is required. Thereby, the work for determining which tape guide to use for a specific component tape is limited to a very quick and simple visual identification, which reduces the time required for associating and loading new component tapes into tape guides, and significantly reduces the risk for selecting the wrong tape guide.
According to one embodiment, the component tape and/or the component tape holder as well as the tape guide are provided with a similar visual marking, e.g. similar or identical labels. According to another embodiment, the component tape and/or the component tape holder are produced with a color or pattern corresponding to the pattern or color of the visual marking of the tape guide. Then, the operator readily realizes that for a red component tape, or component tape holder, a tape guide with a red marking is required. Thereby, the work for determining which tape guide to use for a specific component (tape) is reduced even further to a very quick and simple color identification, and the risk of selecting the wrong tape guide is even further reduced.
As stated above, the base material for the tape may also vary, which normally affects the thickness of the lateral portion of the component tape, i.e. the portion provided with feeding holes. Generally, for plastic tapes, the thickness of the lateral portion of the component tape does not have to be related to the depth or size of the compartments, whereas for cardboard tapes the thickness usually corresponds to the depth of the compartments, which depends on the height of the components to be contained. This is due to the fact that a single, elongated cardboard element is used as the component tape, which is provided with through holes that makes up the feeding holes, as well as the compartments.
Furthermore, the feeding devices used for feeding a component tape in a component mounting process normally comprise feeding pins that is brought into engagement with the feeding holes of the component tapes. Generally, the feeding pins are mounted on the peripheral surface of a feeding wheel or on an arrangement for reciprocating, linear movement of the feeding pins.
According to a preferred embodiment of the invention, the tape guide is further provided with locking elements for mounting the tape guide at the component mounting machine in self-adjusting engagement with corresponding locking elements provided at the component mounting machine, preferably in a component magazine for use with the component mounting machine. The self-adjusting locking elements allows for the vertical position of at least part of the tape guide to be varied in accordance with the configuration of the component tape to be used with the tape guide. Thereby, a controlled lifting force on the component tape can be obtained, in addition to the lifting force provided from engagement of the component exposure device between the cover tape and carrier tape. A resulting increased contact pressure between the upper surface of the component tape and the lower surface of the cover portion of the component exposure device, thus preventing or significantly reducing the risk of components jumping out of their compartments, due to vibrations produced during feeding of the component tape, or from turning on the side or upside-down.
Preferably, said self-adjusting locking elements comprises forward pivotal locking elements, and rearward, displaceable locking elements. Thus, the rearward locking element interacts with corresponding locking elements at the component mounting machine that in a displaceable engagement that permits relative vertical movement or displacement of the rearward locking element. Thereby, the rear of the tape guide may be slightly raised and the tape guide thereby pivoted, while still maintaining a mounted position.
According to a preferred embodiment of the invention, a base surface of the device for feeding the component tape is brought into controlled, pressurized contact with the lateral portion of the component tape, thereby providing said lifting force of the component tape. The base surface is the surface from which the feeding pins for engagement with the feeding holes project. Thus, the components contained in the compartments, that have been exposed by moving the cover tape, that are covered by the above-described cover portion until the compartment reaches the picking position, are efficiently kept from jumping out of their compartments, due to vibrations produced during feeding of the component tape, or from turning on the side or upside-down.
As a consequence of the adjustability of the vertical position of the tape guide, the distance between the upper surface of the feeding device and the lower surface of the cover portion may be automatically adjusted in correspondence with the thickness of the lateral portion of the component tape. Preferably, the rear locking element is in biased engagement with the locking elements at the component mounting machine, whereby an essentially constant contact pressure between the surface of the feeding device and the lateral portion of the component tape.
The rear locking element of the tape guide is preferably in the form of an angled engagement surface interacting with a biased locking element at a component mounting machine. Said biased locking element may be in the form of a biased lever brought into sliding or otherwise displaceable engagement with the engagement surface. However, the described arrangement may be substituted for any biased engagement between locking elements at the component mounting machine, preferably in a component magazine, and the rearward locking elements of the tape guide that provides the desired, vertically displaceable mounting effect.
As understood by the person skilled in the art, the features of the rearward and forward locking elements of the tape guide could be switched such that the forward locking element is displaceable, and the rearward locking element is pivotal.
Further details and aspects of the present invention will become apparent from the following description of preferred embodiments of the invention.